Intermediates for preparing pyrazole derivatives

ABSTRACT

The invention relates to novel intermediates in a process for preparing compounds having the formula: wherein R3, R4, R6 and Ar are as defined in the description, by reaction of a compound of formula (I) with a compound of formula (II) according to the following reaction scheme: The compounds of formula (IV) are useful as pesticides.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application No. 08/815,848,filed Mar. 12, 1997, U.S. Pat. No. 5,907,041.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The instant invention is directed to novel intermediates in a newprocess for manufacturing pesticidally active materials. Moreparticularly, the instant invention is directed to intermediates in aprocess for manufacturing 1-aryl substituted pyrazoles.

2. Background Art

Many manufacturing processes have been described in the literature forpreparing such derivatives, for example in International PatentPublication Nos. WO87/03781, WO93/06089 and WO94/21606; in EuropeanPatent Publication Nos. 0295117, 0403300, 0385809 and 0679650; U.S. Pat.Nos. 5,232,940 and 5,236,938; and German Published Patent ApplicationNo. 19511269.

The Japp-Klingemann reaction, reviewed in Org. React., Vol. 10, pages143-178 (1959), known in the literature since 1887, is a process bywhich phenyl azo compounds are formed from the reaction of diazoniumsalts with active methylene compounds. Typically the phenyl azo compoundis not isolated, but is reacted in situ with base resulting in loss of aleaving group and formation of the corresponding hydrazone. When thephenyl azo intermediate is properly substituted, a spontaneouscyclization reaction occurs giving a3,5-disubstituted-4-protio-pyrazole, that is, a3,5-disubstituted-4-unsubstituted pyrazole. If a 3,4,5-trisubstitutedpyrazole is desired, further manipulation is required in subsequentsteps.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the instant invention is to provide a new manufacturingprocess for preparing arylpyrazole derivatives.

Another object of the instant invention is to provide a simplemanufacturing process, if possible, more simple than the existingprocess.

These objects are met in whole or in part by the instant invention.

This invention provides a new and more efficient process for the directpreparation of 3,4,5-trisubstituted-1-arylpyrazoles. Surprisingly, ithas been found that the pyrazole ring cyclization of certain aryl azointermediates proceeds such that the leaving group (normally lost inthese type of reactions) is reincorporated into the pyrazole at C-4 thusgiving immediate access to 3,4,5-trisubstitated-1-arylpyrazoles. Thisoffers advantages in reducing the number of reaction steps required toproduce the desired pesticidally active3,4,5-trisubstituted-1-arylpyrazole derivatives, which in turn meansless waste chemical may be generated when manufacturing such compounds;and less energy may be needed. This also helps to reduce themanufacturing cost of the pesticidally active 1-aryl pyrazolederivatives.

The invention thus provides a process for preparing 1-arylpyrazolesaccording to the following reaction scheme: ##STR3## wherein: Ar isoptionally substituted phenyl or optionally substituted pyridyl;

X is a compatible anion;

R₃ represents --C(O)R₈, --CN, --CO₂ H, --C(O)NHR₈, --CHO, --C(O)CO₂ R₈,--S(O)_(m) R₈, --C(O)CH₂ Het, Het, --C(O)CH₂ R₉, --C(O)alkyl,--C(O)haloalkyl, --C(O)styryl, halogen, --C(O)OR₈, --P(O)(OR₈)₂,--P(S)(OR₈)₂, --NO₂, R₉ or --S(O)_(m) styryl;

R₄ is as defined for R₃ excluding --CN and halogen;

m is 0, 1, or 2;

R₅ is --CN, --C(O)OR₈ or --C(O)-alkyl;

R₆ is --NH₂, --OH, or alkyl;

R₈ is alkyl, haloalkyl, R₉ or Het;

Het represents a 5- or 6-membered heterocyclic ring, said ring havingfrom one to three ring heteroatoms which are the same or differentselected from the group consisting of nitrogen, sulfur and oxygen, eachcarbon atom of said ring being unsubstituted or being substituted byhalogen, alkyl, haloalkyl, alkoxy, haloalkoxy, cyano, nitro, amino,N-alkylamino, N,N-dialkylamino, OH, --S(O)_(m) alkyl or --S(O)_(m)haloalkyl; and

R₉ represents phenyl optionally substituted by one or more membersselected from the group consisting of halogen, alkyl, haloalkyl, alkoxy,haloalkoxy, cyano, nitro, amino, N-alkylamino, N,N-dialkylamino, --OH,--S(O)_(m) alkyl, and --S(O)_(m) haloalkyl.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

In the specification the following terms have the general meanings givenbelow:

"alkyl" is branched or straight chain alkyl having from 1 to 6 carbonatoms;

"haloalkyl" is branched or straight chain alkyl having from 1 to 6carbon atoms, bearing one or more halogen which are the same ordifferent;

"alkoxy" is branched or straight chain alkoxy having from 1 to 6 carbonatoms;

"haloalkoxy" is branched or straight chain alkoxy having from 1 to 6carbon atoms, bearing one or more halogen which are the same ordifferent;

"halogen" means fluorine, chlorine, bromine or iodine.

In the definition above it will be understood that R₄ cannot represent--CN or halogen because in formula (III) above, --CN or halogen cannotmigrate to the adjacent carbon atom in the rearrangement step to givethe compound of formula (IV) above.

X can be any anion compatible with the reaction conditions prevailing.Examples of suitable groups include (HSO₄), halogen, (BF₄), (ZnCl₃) and(CoCl₃). Preferably X is halogen or (HSO₄).

When Ar is phenyl, it has from 0 to 5 substituents. When Ar is pyridyl,it has from 0 to 4 substituents. Preferably, Ar has from 1 to 3substituents. In any event, the optional Ar substituents are preferablyselected from the group consisting of halogen, CN, NO₂, haloalkyl,haloalkoxy, S(O)_(m) CF₃, SF₅ and R₁₀ wherein m is as defined above andR₁₀ is as defined below.

Preferably Ar is a group having the formula ##STR4## wherein: Zrepresents a trivalent nitrogen atom or a C--R₇ radical, the other threevalences of the carbon atom forming part of the aromatic ring;

R₁ and R₇ represent, independently of each other, a hydrogen or halogenatom, or CN or NO₂ ;

R₂ represents halogen, haloalkyl, haloalkoxy, S(O)_(m) CF₃, SF₅ or R₁₀ ;

and R₁₀ is phenyl optionally having from one to five substituentsselected from the group consisting of halogen; alkyl; haloalkyl;cyanoalkyl; cyano; nitro; amino; hydrazino; alkoxy; haloalkoxy;haloalkylcarbonyl; formyl; alkylcarbonyl; thiocarbamoyl; carbamoyl;alkoxycarbonyl; SF₅ ; and R₈ S(O)_(m) (preferably the 4-positionsubstituent being halogen, haloalkyl or haloalkoxy); two adjacent phenylsubstituents being optionally joined together form a 1,3-butadienylene(--CH═CH--CH═CH--), methylenedioxy (--O--CH₂ --O--) orhalomethylenedioxy (e.g., --O--CF₂ --O--) group so as to form a cyclicring vicinal to the phenyl ring.

The following are also preferred embodiments of the invention,especially when Ar is one of the preferred groups depicted above:

R₃ is --CN or --COR₈ ; and/or

R₄ is --S(O)_(m) R₉, --S(O)_(m) alkyl or --S(O)_(m) haloalkyl; and/or

R₅ is --CN; and/or

R₆ is --NH₂.

The following value of the various substituents provide representativecompounds of formulae (I) to (IV) above. In the Table that follows "Ph"means phenyl; "Pyr" means pyridyl; "Et" means ethyl.

    ______________________________________                                        Ar            X      R.sub.3 R.sub.4  R.sub.5                                                                           R.sub.6                             ______________________________________                                        2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            COCH.sub.3                                                                            SO.sub.2 (4-Cl Ph)                                                                     CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      SO.sub.2 (4-Cl Ph)                                                                     CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      CO.sub.2 Et                                                                            CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      SOCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      SOCH.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-OCF.sub.3 Ph                                                                Cl     Cl      SOCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      SOEt     CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      P(O)(OEt).sub.2                                                                        CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 Cl     CN      SO.sub.2 CF.sub.3                                                                      CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            SO(4-   COCH.sub.3                                                                             CN  NH.sub.2                                                 Cl Ph)                                                   2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      COCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      NO.sub.2 CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            NO.sub.2                                                                              COCH.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            SO.sub.2 (2-                                                                          COCH.sub.3                                                                             CN  NH.sub.2                                                 thienyl)                                                 2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            COCH.sub.3                                                                            SO.sub.2 (2-thienyl)                                                                   CN  NH.sub.2                            2,6-Cl.sub.2 -4-(4-Cl Ph) Ph                                                                HSO.sub.4                                                                            CN      SOCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            Br      COCH.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            Br      COPh     CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      CO(2-furyl)                                                                            CN  NH.sub.2                            2,6-Cl.sub.2 -4-CF.sub.3 Ph                                                                 HSO.sub.4                                                                            CN      SOCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-SF.sub.3 Ph                                                                 HSO.sub.4                                                                            COCH.sub.3                                                                            SO.sub.2 (4-Cl Ph)                                                                     CN  NH.sub.2                            2,6-Cl.sub.2 -4-SF.sub.5 Ph                                                                 HSO.sub.4                                                                            CN      SO.sub.2 (4-Cl Ph)                                                                     CN  NH.sub.2                            2,6-Cl.sub.2 -4-SF.sub.5 Ph                                                                 HSO.sub.4                                                                            CN      CO.sub.2 Et                                                                            CN  NH.sub.2                            2,6-Cl.sub.2 -4-SF.sub.5 Ph                                                                 HSO.sub.4                                                                            CN      SOCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-SF.sub.5 Ph                                                                 HSO.sub.4                                                                            CN      SOCH.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-SF.sub.5 Ph                                                                 Cl     Cl      SOCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-SF.sub.5 Ph                                                                 HSO.sub.4                                                                            CN      SOEt     CN  NH.sub.2                            2,6-Cl.sub.2 -4-SF.sub.5 Ph                                                                 HSO.sub.4                                                                            CN      P(O)(OEt).sub.2                                                                        CN  NH.sub.2                            2,6-Cl.sub.2 -4-(4CF.sub.3 Ph) Ph                                                           HSO.sub.4                                                                            CN      SOCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-(4-OCF.sub.3 Ph) Ph                                                         HSO.sub.4                                                                            CN      SOCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-O Ph                                                                        HSO.sub.4                                                                            CN      SOCF.sub.3                                                                             CN  NH.sub.2                            2,6-Cl.sub.2 -4-(4-SCF.sub.3 Ph) Ph                                                         HSO.sub.4                                                                            CN      SOCF.sub.3                                                                             CN  NH.sub.2                            ______________________________________                                    

The process of the invention is generally conducted in two steps,although it may be carried out as a continuous process including thein-situ rearrangement of the compound of formula (III) to give acompound of formula (IV). This in-situ process may be preferred when theprocess forms part of a manufacturing process, as it may avoid the needfor isolation of the intermediate of formula (II).

In the first step the diazonium salt (I) is reacted with a compound (II)in a solvent, with protic solvents such as methanol, ethanol and aceticacid being preferred. The reaction is performed, optionally in thepresence of a base, at a temperature between about 0° and about 120° C.,preferably between about 0 and about 25° C., to give the azo product(III). When base is used in this step, it can be organic such aspyridine or triethylamine, or inorganic such as potassium carbonate orsodium hydroxide. When used, the amount of base is generally from about1 to about 25 equivalents [based on the mole equivalents of the compoundof formula (I)], with about 1 to 5 equivalents being preferred.

In the second step of the reaction sequence, the azo compound (III) isdissolved in a suitable solvent and optionally subjected to up to about20 equivalents of a base, preferably up to about 5 equivalents, to givethe rearranged pyrazole of formula (IV). The reaction temperature forthis step is from about 0 to about 120° C., preferably from about 0 toabout 25° C. The solvent can be protic such as methanol, ethanol oracetic acid, or preferably the solvent can be aprotic, such asdichloromethane, tetrahydrofuran, or toluene. Suitable bases may beorganic (such as pyridine, triethylamine, or piperidine), inorganic(such as sodium hydroxide, potassium carbonate, sodium hydride) ororganometallic (such as potassium t-butoxide, sodium methoxide, lithiumdiisopropylamide), with organic or organometallic bases being preferred.

The compound of formula (III) above is generally present in a molarexcess. Preferably from about 1 to about 2 moles of the compound offormula (III) are present, more preferably from about 1.05 to about 1.1moles.

Compounds of formula (III) in which Ar, R₃, R₄ and R₅ are as definedabove, provided that when R₃ and R₅ are both cyano R₄ is not --C(O)OR₈,are novel and thus constitute a feature of the present invention.

Compounds of formula (II) may be prepared by the reaction of a compoundof formula (V):

    R.sub.3 --CH.sub.2 R.sub.4                                 (V)

wherein R₃ and R₄ are as defined above with a compound of the formula R₅CH₂ L wherein R₅ is as defined above and L is a leaving group, in thepresence of a base. Examples of suitable leaving groups include halogenand tosylate (preferably halogen). The base is generally a strong base(e.g. sodium hydride or n-butyl lithium) and the reaction is generallyperformed in an aprotic solvent (e.g. tetrahydrofuran) at a temperaturefrom about -78° C. to about 0° C. Compounds of formula (II), in which R₅is cyano and R₃ and R₄ are as defined above, provided that when R₃ is--CN then R₄ is not --C(O)OR₈, are also novel and thus constitute afurther feature of the present invention.

The following non-limiting examples illustrate the invention.

EXAMPLE 1

Preparation of 3-(4-chlorophenylsulfonyl)-4-cyanobutan-2-one

To a 300 mL reaction flask was added 2.4 g (59.3 mmole) sodium hydride(60% dispersion in oil) and 10 mL hexanes. The hexanes were removed bypipette and replaced by 60 mL dry tetrahydrofuran (THF). The suspensionwas cooled to -15° C. and a solution of 12.0 g (51.6 mmole)4-chlorophenylsulfonyl acetone in 50 mL THF was added via additionfunnel over 20 minutes maintaining the reaction temperature below -12°C. The resulting yellow solution was removed from the cold bath andstirred at room temperature for 30 min. The solution was recooled to -5°C. and 3.8 mL (54.1 mmole) bromoacetonitrile was added dropwise viaaddition funnel. After 5 min, the reaction mixture was removed from thecold bath and stirred at room temperature overnight. The reaction wasquenched with 1 mL of saturated ammonium chloride and transferred with100 mL of dichloromethane to a separatory funnel containing 100 mLbrine. The organic layer was separated and the aqueous layer was backextracted once with 50 mL more dichloromethane. The combined organicswere then dried with sodium sulfate, filtered, concentrated, andchromatographed through a bed of silica gel using 1:1hexane:dichloromethane. Isolation gave 8.2 g (59% yield) of3-(4-chlorophenylsulfonyl)4-cyanobutan-2-one, a yellow oil that was 90%pure by HPLC. ¹ H NMR (CDCl₃) indicated desired product as the majorcomponent: δ7.6 (m, 4H), 4.42 (dd, 1H), 2.78 (m, 2H), 2.48 (s, 3H).

EXAMPLE 2

Preparation of3-(4-chlorophenylsulfonyl)-3-[(2,6-dichloro-4-trifluoromethlphenyl)azo]-4-cyanobutan-2-one

To a 250 mL reaction flask was added 2.0 g (35.7 mmole) potassiumhydroxide pellets followed by 30 mL water and 30 mL methanol. To thissolution was added 6.9 g (25.5 mmole) of compound3-(4-chlorophenylsulfonyl)-4-cyanobutan-2-one. Once homogeneous, 23.2mmole of the hydrogensulfate diazonium salt of2,6-dichloro-4-trifluoromethylaniline was added in one portion to thereaction medium. After stirring for 45 minutes at room temperature thereaction mixture was worked-up by adding water and dichloromethane. Thelayers were separated and the organic layer back extracted once withdichloromethane (50 mL). The combined organics were dried (Na₂ SO₄),filtered, concentrated and chromatographed through silica gel usinghexane:ethyl acetate mixture. Isolation gave 5.1 g (43%) the titlecompound as a glassy semi-solid which HPLC indicated was 98% pure and ¹HNMR indicated as desired product: δ7.6 (m, 4H), 7.65 (s, 2H), 3.3 (dd,2H), 2.42 (s, 3H).

EXAMPLE 3

Preparation of3-acetyl-5-amino-4-(4-chlorophenyl)sulfonyl-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole

Two drops of triethylamine were added to 0.51 g (1.0 mmole)3-(4-chlorophenylsulfonyl)-3-(2,6-dichloro-4-trifluoromethylphenylazo)-4-cyanobutan-2-onedissolved in 10 mL dichloromethane. After stirring overnight at roomtemperature, the reaction was worked-up by adding additionaldichloromethane and washing with water. The organic layer was separated,dried (Na₂ SO₄), filtered and concentrated to give 0.55 g of the titlecompound that was 94% pure by HPLC, m.p. 158° C.

EXAMPLE 4

Preparation of 2-(4-chlorophenylsulfonyl)succinonitrile

To a 500 mL reaction flask was added 2.0 g (51.0 mmole) sodium hydride(60% dispersion in oil) and 20 mL hexanes. The hexanes were removed bypipette and replaced by 90 mL dry tetrahydrofuran (THF). The suspensionwas cooled to 0° C. and a solution of 10.0 g (46.4 mmole)4-chlorophenylsulfonyl acetonitrile in 90 mL THF was added via additionfunnel over 10 minutes maintaining the reaction temperature below 12° C.The resulting solution was removed from the cold bath and stirred atroom temperature for 40 min. The solution was recooled to 0° C. and 3.4mL (48.7 mmole) bromoacetonitrile in 5 mL THF was added dropwise viaaddition funnel. After 5 minutes, the reaction was removed from the coldbath and stirred at room temperature for two hours. The reaction wasquenched with 1 mL of saturated ammonium chloride and concentrated to anoil which was transferred with 150 mL of dichloromethane to a separatoryfunnel containing 120 mL water. The organic layer was separated andwashed once more with 120 mL water and once with 120 mL brine. Theorganic layer was then dried (Na₂ SO₄), filtered, concentrated, andchromatographed through a bed of silica gel using 85:15 hexane:ethylacetate. Isolation gave 1.4 g (12% yield) of the title compound as ayellow powder that was 96% pure by HPLC, m.p. 130-137° C.

EXAMPLE 5

Preparation of2-(4-chlorophenylsulfonyl)-2-(2,6-dichloro-4-trifluoromethyl)phenylazosuccinonitrile

To a 50 mL reaction flask was added 0.45 g (1.77 mmole) of2-(4-chlorophenylsulfonyl)succinonitrile in 15 mL methanol. Oncehomogeneous, 1.61 mmole of the hydrogensulfate diazonium salt of2,6-dichloro-4-trifluoromethylaniline was added in one portion to thereaction medium. After stirring 45 min at room temperature the reactionmixture was worked-up by adding brine and dichloromethane. The layerswere separated and the organic layer was dried (Na₂ SO₄), filtered,concentrated and chromatographed through silica gel using 90:10hexane:ethyl acetate. Isolation gave 0.33 g (42%) of the title compound,a red crystalline solid which ¹⁹ F NMR indicated was over 95% pure, m.p.45-50° C.

EXAMPLE 6

Preparation of5-amino-3-cyano-4-(4-chlorophenylsulfonyl)-1-(2,6-dichloro-4-trifluoromethylphenyl)pyrazole

Three drops of triethylamine were added to 0.3 g (0.61 mmole) of2-(4-chlorophenylsulfonyl)-2-(2,6-dichioro-4-trifluoromethyl)phenylazosuccinonitrile in 20 mL dichloromethane. After stirring two hours atroom temperature the reaction was worked-up by diluting withdichloromethane and partitioning from water. The layers were separatedand the aqueous layer was back-extracted once with dichloromethane. Thecombined organics were dried (Na₂ SO₄) filtered, concentrated andchromatographed through silica gel eluting with 90:10 hexane:ethylacetate. Isolation gave 0.14 g (47% yield) of the title compound, 100%pure by HPLC as an orange foam, m.p. 90-95° C.

EXAMPLE 7

Preparation of ethyl2,3-dicyano-2-(2,6-dichloro-4-trifluoromethyl)phenylazo propionate

22.1 Mmole of ethyl dicyanopropionate in 20 mL absolute ethanol wascooled to 0° C., and 20.9 mmole of the hydrogensulfate diazonium salt of2,6-dichloro-4-trifluoromethylaniline was added via addition funnel over15 minutes. The reaction was warmed to room temperature and stirredovernight. The reaction was worked-up by adding water anddichloromethane. The layers were separated and the aqueous layer wasback extracted once with dichloromethane. The combined organics werewashed once with brine and the organic layer was dried (Na₂ SO₄),filtered, concentrated and chromatographed through silica gel using90:10 hexane:ethyl acetate. Isolation gave 2.7 g (33%) of the titlecompound as a red viscous oil which contained 82% desired azo productand 13% of the corresponding hydrazone. ¹ H NMR (CDCl₃) indicateddesired product as the major component: δ7.70 (s, 2H), 4.44 (m, 2H),3.58 (q, 2H), 1.39 (t, 3H).

EXAMPLE 8

Preparation of5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)4-carboethoxyprazole

To a 100 mL reaction flask was added 0.51 g (1.30 mmole) ethyl2,3-dicyano-2-(2,6-dichloro-4-trifluoromethyl)phenylazo propionate in 20mL tetrahydrofuran. The reaction was cooled to -78° C. and 0.52 g (1.30mmole) sodium hydride (60% dispersion in oil) was added in one portion.The reaction mixture warmed to room temperature overnight. Two grams ofsilica gel and 40 mL ethyl acetate were added to the reaction mixtureand the slurry was concentrated and chromatographed through silica geleluting with 90:10 hexane:ethyl acetate (1 L) and 80:20 (2 L). Isolationgave 0.16 g (38% yield based on 82% pure starting material), a solidthat was 99% pure by HPLC, m.p. 201.5-202.5° C.

EXAMPLE 9

Preparation of Hydrogensulfate Diazonium salt of2,6-dichloro-4-trifluoromethylaniline

To a 100 mL reaction flask was added 5.3 g (23.2 mmole)2,6-dichloro-4-trifluoromethylaniline dissolved in 45 mL glacial aceticacid. The solution was cooled in an ice water bath and 3.8 g (30.1mmole) nitrosylsulfuric acid was added in one portion. The reaction wasremoved from the ice bath and stirred at room temperature for two hours.The resulting diazonium salt was used without purification.

The compounds of formula (IV) prepared by the process of the presentinvention are useful as pesticides.

While the invention has been described in terms of various preferredembodiments, the skilled artisan will appreciate that variousmodifications, substitutions, omissions and changes may be made withoutdeparting from the spirit thereof. Accordingly, it is intended that thescope of the present invention be limited solely by the scope of thefollowing claims, including equivalents thereof.

What is claimed is:
 1. The compound whichis:3-(4-chlorophenylsulfonyl)-3-(2,6-dichloro-4-trifluoromethylphenylazo)-4-cyanobutan-2-one;or2-(4-chlorophenylsulfonyl)-2-(2,6-dichloro-4-trifluoromethyl)phenylazosuccinonitrile.